disbandment of the 10th Cruiser Squadron on 29 November 1917, the ships of the Northern Patrol inspected almost 13,000 merchant vessels at sea and only 642 ships managed to elude the blockade. The cruiser HMS Hawke and ten AMCs (including Avenger) were lost. In 1980, A. Cecil Hampshire wrote that the blockade is generally considered to have been one of the main causes of the defeat of Germany in the First World War. Second World War Mobilisation In June 1939 the Admiralty began to call up reservists, 12,000 for the Reserve Fleet, as its ships were prepared to return to service; by 9 August the ships had received their complement of crews. The light cruisers were far from new, most being C-class cruisers and D-class cruisers of , built during the First World War. The ships had five or six 6-inch (152 mm) guns, two 3-inch (76 mm) guns, four 3-pounder (47 mm) guns and eight 21-inch (533 mm) torpedo tubes; the ships had a maximum speed of . The ships had been designed for operations in the North Sea but had soon been sent onto far rougher waters. Six of the vessels had been used as boys' training ships. Two Emerald class light cruisers and the Hawkins-class cruiser , the flagship of the Admiral Commanding, Northern Patrol, Vic-Admiral Max Horton were added. The Northern Patrol was re-established on 6 September 1939, three days after the start of the Second World War. Its area of operations was more extensive than during the First World War and included the areas north of Scotland and Ireland, between the north of Scotland and Norway, around Shetland, the Faeroe Islands and Iceland and the Denmark Strait between Iceland and Greenland. Armed merchant cruisers soon replaced the light and heavy cruisers. As in the First World War, warships from the Home Fleet or other commands were temporarily attached to the Northern Patrol. The force operated within the command area of the Vice-Admiral or Rear-Admiral Commanding in the Orkneys and Shetlands who administered the islands and commanded the defences of Scapa Flow but was not subordinate to him. Cruiser squadrons 1939–1940 The three cruiser squadrons were supplemented and then replaced by armed merchant cruisers, the survivors of which were dispersed to other duties between late 1940 and 1941. Commanders, Northern Patrol Second Northern Patrol By October 1939 the Admiralty had requisitioned 51 ships for use as